1. Field of Invention
The present invention relates to an integrated circuit device and a method of fabricating the same, and more particularly to a self-aligned contact and a method of fabricating the same.
2. Description of Related Art
Along with the development of science and technology, the integration of electronic devices must be improved to meet the trend of light, thin, short, and small electronic devices. In addition to reducing the size of the semiconductor devices, the method of improving the integration can also be achieved by reducing the distance between semiconductor devices. However, some process problems are unavoidable no matter the size of the semiconductor devices or the distance between the semiconductor devices is reduced.
As for a contact process, after the contact is downsized, the aspect ratio of the contact is increased, such that the etching becomes difficult and the process window becomes small. In order to remove the residual in the etching process and keep contact opening open through to the contact region, generally, a long time over-etching is performed to avoid that the contact opening cannot be fully opened through to the contact region. However, during a lithography process, misalignment often occurs, and the contact opening always forms a tilted angle with respect to the vertical surface of the substrate. If the over-etching takes a long time, a top corner of a gate may be exposed easily, resulting in that the metal layer filled in the contact opening is electrically connected to the gate and a source/drain region and causing short circuit.